Treatment of bark



Patented July 28, 1942 TREATMENT OF BARK Arthur J. Gorman, Bartlesvillc, Okla, assignor to Frank Phillips, New York, N. Y.

No Drawing.

Application November 21, 1939,

Serial No. 305,558

6 Claims.

This invention relates to the treatment of bark and more particularly to the treatment and application of bark to a wood base.

It has generally been the practice to manufacture rustic furniture and other equipment by one of two commonly known methods. The earliest method includes cutting bark covered timber into slabs and constructing a particular article with the slabs arranged so that the bark is exposed to view. This has been unsatisfactory as it is virtually impossible to obtain large surfaces of properly matched bark in this manner; and furthermore, the bark will in time curl and crack off due to the aging and drying of the bark and wood. While nailing may in some cases retard this eventuality, it is at best but a make shift as it does not afford a lasting solution to the problem. The other method contemplates peeling strips of bark from logs and nailing them in place by means of fine brads. This procedure, while an improvement over the first mentioned method, also has its objections. In the first place, this method is costly and tedious. Then again, as the bark ages, it tends to shrink and become checked and cracked. Another disadvantage to both methods resides in the fact that various insects, including the common brown beetle and its larvae, feed on and bore into the bark, thereby either partially damaging or completely destroying the same.

My present invention obviates all the objections experienced heretofore and provides a method whereby bark may be satisfactorily worked, properly preserved and successfully applied to a wood, base without impairing the natural beauty of the bark. A number of articles of furniture, such as clocks, picture frames, buffets and grand pianos have been covered with bark which was treated and applied in accordance with the teachings of my invention. It might be stated at this time that the results in each instance were uniformly excellent and entirely satisfactory. As will be more fully explained hereinafter, my invention in its broad aspects contemplates immersing strips of bark in a boiling solution of water, horn glue, zinc chloride and copper sulphate for a sufficient length of time to permit the solution to impregnate the bark; removing the thin tissue on the under surface of the bark by scraping or otherwise; shaping the bark, while wet and hot, to any desired form; drying the bark to substantially dehydrate the same; and then applying the bark to a seasoned wood base by means of an adhesive substance containing horn 'glue.

It is the primary object of this invention to provide a method of properly and effectively treating and applying bark to wood.

Another object of this invention is to treat bark so that it can be successfully and satisfactorily shaped.

This invention has for a further object the treatment and application of bark to a wood base in such a manner that shrinking, curling, flaking and/ or checking, due to aging, will be eliminated.

A still further object of this invention is to provide a bark veneered wood which is resistant to the injurious and deleterious effects of insects, worms and changes in the moisture content of the atmosphere.

These and additional objects and advantages will be readily apparent to those skilled in the art by reference to the following description which contains a detailed recitation of the several steps comprising the invention.

It should be borne in mind at the outset that the bark of various trees and plants may be treated and applied to a wood base by following the teachings of my invention. While the bark of long leaf yellow pine and short leaf yellow pine may be employed advantageously, the bark of many other trees and plants, including northern white pine and sugar pine, may be employed with equally fine results. Also, the Wood base to which the bark is applied may be any one of a variety of domestic or imported woods, the only essential requirement being that the same shall be seasoned and dried in order to overcome the possibility of shrinkage and warpage.

I find that bark from timber that has been cut not less than four (4) months and not more than eight (8) months, prior to use, is best suited for my purposes. This period depends on the type and age of the timber, and the temperature and other local conditions under which the timber is stored. Bark covered slabs or loss of the timber are first submerged in hot water for from three (3) to five (5) hours, after which the bark may be readily removed from its wood in the customary manner. The bark, preferably in the form. of strips or squares is next immersed in a boiling aqueous solution including ordinary horn glue, or any other substance containing horn glue as a base, zinc chloride and copper sulphate. For optimum results, th bark remains for a period of approximately thirty (30) minutes in the boiling solution containing, for example, (by weight),

The step of soaking the bark in the above solution serves a three-fold purpose; namely, (1) the bark is toughened and held together so that it can be satisfactorily worked into any desired shape; (II) any fungi, insects, worms, or larvae that may be either on or in the bark are destroyed; (III) the bark becomes infused and imaaaopas pregnated with hom'g'lue, zinc chloride and copper sulphate, thereby affording excellent protection against injury due to insects and changes in atmospheric conditions. There are instances in which the zinc chloride and the copper sulphate ingredients may be omitted from the aqueous solution without materially subtracting from the effectiveness of my treatment. It is recommended, however, that these materials be included in the solution when the treated bark is to be used in localities where the brown beetle and other bark destroying insects prevail,

Upon withdrawing the bark from the aqueous solution, the slimy film on the under surface of the bark is removed by scraping. The bark, while still wet and hot, is manually flexed and worked until it assumes the required configuration. If, for example, it is intended to cover a curved surface with bark, strips and pieces of the bark are manually worked and fitted in matched relation on a form. The bark is maintained on th form by any known expedient and then dried, preferably in a suitable kiln. The purpose of this operation is to dehydrate the bark to the extent that the amount of moisture retained therein shall not exceed 3% of the total weight of the treated bark. Although substantially all the water is thus removed, an appreciable part of the horn glue and chemicals remains in and on th bark, serving as a preservative. Experience has demonstrated that bark which has been thus impregnated with glue, zinc chloride and copper sulphate is highly resistant to the detrimental effects of insects, worms, the larvae of each, and variations in the moisture content of the surrounding atmosphere.

The under surface of the bark is next dressed by means of a suitable plane or other instrument in order to remove the fibrous tissue, leaving the pores in an open and exposed condition. The outer face of the bark may be finished in a similar manner to produce a surface having the desired smoothness, texture and uniformity. The extent to which the outer surface is dressed down is of course dependent on the artistic effect to be created by the completed article. It is obvious that there may be occasions where it is preferable to retain the normal barky appearance, inwhich cases the outer surface is left in its natural state. Whether or not the outer surface is finished, the treatment imparted to the bark will be equally effective against decay.

The bark is now ready for mounting on the seasoned wood base. This is accomplished by coating both the under surface of the bark and the bearing surface of the wood base with a suilicient amount of liquid horn glue to insure complete contact when thesurfao-es are brought together. The temperature of the glue should range between 200 F. and 220 F., in the case of ordinary liquid horn glue, and should not be less than- 60 F., when waterproofing glue is used. Regardless of the type of glue employed, the temperature of the bark and wood base should not be lower than 70 F. while the gluing operation is being carried out. The final step in the procedure consists of placing the barkon the wood base and clamping them together by a conventional clamp until the glue has completely dried, being careful, however, not to bruise any of the exposed surfaces of the bark.

From the foregoing it is believed that the objects, advantages and method of practicing my present invention will b readily comprehended by persons skilled in the art. It is to be clearly understood, however, that my invention as described herein is capable of various changes without departing from the spirit of this invention as defined by the appended claims. For example, although the use of horn glue has been specified, it is to be understood that all other substances having th same properties as horn glue shall be considered as equivalents.

I claim:

1. In the method of treating bark, the steps comprising immersing the bark in an aqueous solution containing from 0.5 to 1 part of glue,

from 0.3 to 1.25 parts of zinc chloride and from 0.3 to 0.5 part of copper sulphate for every parts of water by weight, withdrawing the bark from the solution, shaping the bark to a desired in an aqueous solution including glue, zinc chloride and copper sulphate, withdrawing the bark from the solution, shaping the bark to a desired configuration, dehydrating the bark, and placing the bark on a seasoned wood base with a coating of liquid glue interposed therebetween.

3. In the method of producing a bark veneered wood, the steps comprising immersing the bark in an aqueous solution including glue, zinc chloride and copper sulphate, withdrawing the bark from the solution, shaping the bark to a desired configuration, drying the bark to substantially dehydrate the same, dressing the under surface of the bark, and applying the bark to a seasoned wood base with a coating of liquid glue interposed between the dressed surface of the bark and the wood base.

4. In the method of producing a bark veneered wood, the steps comprising immersing the bark in a solution containing water and glue, withdrawing the barlc from the solution, shaping the bark to a desired configuration, substantially dehydrating the bark, dressing the under surface of the bark, and applying the bark to a seasoned wood base with a coating of liquid horn glue interposed between the dressed surface of the bark and the wood base, the temperature of the liquid glue in the last operation being within the range of 200 to 220 F. and the temperature of the bark and wood base being not lower than 70 F. at the time the bark is applied to the wood base.

-5. In the method of producing a bark veneered wood, the steps comprising immersing the bark in an aqueous solution containing glue, zinc chloride and copper sulphate, withdrawing the bark from the solution, shaping the bark to a desired configuration, substantially dehydrating the bark, dressing the under surface of the bark, and applying the bark to a seasoned wood base with a coating of liquid horn glue interposed between the dressed surface of the bark and the wood base, the temperature of the liquid glue in the last operation being within the range of 200 to 220 F. and the temperature of the bark and wood base being not lower than 70 F. at the time the bark is applied to the wood base.

6. In the method of producing a bark veneered wood, the steps comprising immersing the bark in an aqueous solution containing from 0.5- to 1 part of glue, from 0.3 to 1.25 parts of zinc chloride and from 0.3 to 0.5 part of copper sulphate for every 100 parts of water by weight,

withdrawing the bark from the solution, shaping the bark to a desired configuration, dressing the under surface of the bark, and applying the bark vto-a seasoned wood base with a coating of liquid 

